Olefin Polymerization Catalyst with Bismuth and Electron Donor
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Solution Overview
Problem
Current Ziegler-Natta catalysts for olefin polymerization exhibit non-uniform distribution of active components due to morphology issues in carrier materials, leading to low polymerization activity, particularly in random propylene/ethylene copolymers.
Innovation Solution
A solid catalyst component comprising titanium, bismuth, magnesium, halogen, and an electron donor compound is synthesized through a process involving the dissolution of magnesium alkoxide in an organic medium, reaction with TiCl4, and subsequent heating to form spheroidal particles, with bismuth and bidentate electron donors being introduced at various stages to enhance homogeneity and activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ZN catalyst preparation methods using MgCl2 carrier are used, then catalyst can be formed, but non-uniform distribution of active components occurs due to morphology issues in carrier materials
Solution Approach 1:
The invention changes the physical and chemical parameters of the catalyst preparation process by dissolving Mg(OR)2 in organic liquid medium and reacting with TiCl4 to form a homogeneous solution, then controlling the solidification process to create uniform spherical particles. This solution-based approach with controlled parameters ensures uniform distribution of Ti and electron donor compounds throughout the catalyst particle, resolving the non-uniform distribution problem while maintaining high polymerization activity.
Solution Approach 2:
The invention creates a composite catalyst system combining Mg(OR)2, TiCl4, electron donor compounds, and optional Bi compounds in a controlled matrix. This composite structure ensures homogeneous distribution of all active components throughout the catalyst particle, eliminating the non-uniform distribution issues associated with conventional MgCl2 carrier materials while enhancing both polymerization activity and copolymerization performance.
2Manufacturing precision
If solid particles are prepared by solution process with Mg and Ti, then good homogeneity is achieved, but polymerization activity for random propylene/ethylene copolymers remains relatively low
Solution Approach 1:
The invention optimizes the composition parameters by incorporating specific ratios of Mg(OR)2, TiCl4, electron donor compounds, and Bi compounds. The controlled solidification process parameters (temperature, rate) are optimized to create a catalyst structure that maintains the homogeneity achieved during solution preparation while enhancing the polymerization activity for random copolymers, thereby resolving the contradiction between uniformity and reactivity.
Solution Approach 2:
The invention introduces Bi compound as an intermediary element that mediates between the homogeneous catalyst structure and the polymerization reaction. The Bi compound, when present in the catalyst system, enhances the activity for random propylene/ethylene copolymerization while maintaining the homogeneous distribution of active components, thus resolving the low activity issue without sacrificing the homogeneity advantage.
3Ease of manufacture
If MgCl2 carrier is used with transition metal compound, then catalyst component is formed, but morphology of carrier determines final catalyst morphology leading to non-uniform active component distribution
Solution Approach 1:
Instead of forming the catalyst by coating transition metal compounds onto a pre-formed MgCl2 carrier (conventional approach), the invention inverts the process by first creating a homogeneous solution containing Mg(OR)2, TiCl4, and electron donor compounds, then solidifying this solution to form the catalyst particles. This inversion eliminates the morphology transfer problem from carrier to catalyst, ensuring uniform active component distribution while maintaining ease of manufacture through a streamlined single-step process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resulting catalyst demonstrates improved polymerization activity, achieving yields exceeding 140Kg/gcat and producing polymers with high isotactic index and broad molecular weight distribution.
Implementation Method 1
dissolving a Mg(OR)2 compound where R groups, equal or different to each other, are C1-C15 hydrocarbon groups optionally containing a heteroatom selected from O, N and halogen, in an organic liquid medium in order to have a liquid mixture
Implementation Method 2
subjecting the liquid mixture (b) to a temperature of at least 50°C thereby forming solid catalyst particles
Implementation Method 3
contacting the above mixture (a) with TiCl4 obtaining a liquid mixture not containing solid phase
Data Source
AI summary
A solid catalyst component for the polymerization of olefins CH2 =CHR in which R is hydrogen or a hydrocarbon radical with 1-12 carbon atoms, comprising Mg, Ti, Bi, halogen and an electron donor obtained from a process comprising: (a) dissolving a Mg(OR)2 compound where R groups, equal or different to each other, are C1-C15 hydrocarbon groups optionally containing a heteroatom selected from O, N and halogen, in an organic liquid medium in order to have a liquid mixture; (b) contacting the above mixture (a) with Ti Cl4 obtaining a liquid mixture not containing solid phase, and (c) subjecting the liquid mixture (b) to conditions such that solid catalyst particles are formed, said process being characterized by the fact that (i) a Bi compound and (ii) a bidentate electron donor compound is present in one or more of steps (a) to (c) and/or contacted with the solid catalyst particles obtained from (c).